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Everyone knows that kisses taste sweet. Still, a team of researchers from the National University of Singapore felt compelled to prove it. In their study, published last month in the journal Emotion, they investigated the common understanding that emotion is linked to taste. The simple questions they asked: Does love taste sweet? If so, might jealousy taste sour?

Four Experiments

In one experiment, the researchers asked 37 participants to compare different tastes as they applied to specific emotions. The participants rated on a scale of one (not related) to seven (highly related) whether sweet, sour, bitter, salty, and spicy could be compared to love, jealousy, passion, sadness, and betrayal. In a second experiment, the researchers asked 102 participants a series of questions: “If ____ were a taste, what taste would it be?” The fill-in-the-blank emotions were love, jealousy, sadness, betrayal, and passion and participants wrote down at least two tastes for each. Both experiments resulted in the same conclusion: participants paired love with sweetness, while jealousy was most often coupled with sourness and bitterness.

In subsequent experiments, the researchers informed a new round of volunteers that they were conducting consumer taste preference studies. The researchers asked participants to write about a time they felt romantic love. Afterwards, participants were given either a candy that was equally sweet and sour or a candy that was equally sweet and bitter and asked: How sweet, bitter, sour, spicy, and salty is the candy on a one to seven scale? This experiment was repeated with two other groups of participants who either wrote about a time they felt romantic jealousy or a neutral topic: landmarks in Singapore. As one might expect, the participants who had been encouraged to dwell on love rated their candies significantly sweeter than those encourage to dwell on either jealousy or a non-emotional topic. In a surprise twist, the volunteers who had been encouraged to dwell on jealousy did not perceive their candies to taste more sour or bitter than the other participants.

Links to the anterior cingulate cortex?

In a final experiment, one group of volunteers wrote about an event that made them happy, while another group wrote about romantic jealousy, and a third group wrote about love. All 93 participants then tasted a ‘new product’ and, as in the previous experiments, they rated how sweet, bitter, sour, spicy, or salty it was. (The ‘product’ was distilled water.) Again, the volunteers who had been encouraged to feel love rated the water as sweeter than those who had been primed to feel either jealousy or happiness.

“These findings imply that emotions can influence basic perceptual judgments,” wrote the authors and based on the results of this research, lead author Kai Qin Chan extended his hypothesis one step further. "It is possible that when one experiences love, the anterior cingulate cortex would activate representations associated with sweetness, thereby eliciting sweetness sensations even without actual sweetness input," Chan told Real Clear Science.

The anterior cingulate cortex is known to be active in a variety of cognitive and emotional tasks — yet it is also involved in autonomic functions, such as blood pressure and heart rate. In an unrelated study conducted at Wake Forest University, researchers discovered that when participants meditated to relieve anxiety, the parts of their brains that had been activated during meditation were the anterior cingulate cortex and the ventromedial prefrontal cortex. Surprisingly, when activity increased in the anterior cingulate cortex, anxiety decreased. This adds complexity to the understanding of the anterior cingulate cortex as the location of thought and feeling, because clearly it also plays a role in the regulation of emotions.

A final question remains at least for some researchers: What does anxiety taste like?